In conventional cabin architectures of aircraft, the seats and accordingly also the seat rows are arranged at fixed seat positions, i.e. aircraft usually have a fixed cabin architecture. To each seat row there is usually assigned a respective oxygen module. Accordingly, each of the oxygen modules is normally arranged and installed above the seat row assigned to it. For this purpose, the oxygen modules are normally connected to a supply duct extending in the aircraft.
In order to be able to carry more or fewer passengers, if required, in subregions of the aircraft cabin or the entire aircraft cabin, increasingly a more flexible cabin layout is sought. For this purpose, the seats may be displaced to increase or decrease the seat spacing in the longitudinal direction of the aircraft. In order to ensure the correct assignment between oxygen module and seat row, it is desirable for all the required oxygen modules to be installed on board the aircraft. To check the correct layout of the variable cabin architecture, it is desirable to ascertain whether each oxygen module is situated at the respectively correct position (in the longitudinal direction of the aircraft) above the seat row assigned to it.